Process for the alkylation of isoparaffins



June 16, 1942.

F. D. PARKER PROCESS FOR THE ALKYLATION OF ISOPARAFFINS Filed Jam. :50,1939 @wu Y uw REBS NS@ QN mw e INVENTUR. Farrandl). Parker A TTURNEY wm,NU N ow mm. n

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Patented June l 16, 1942 PROCESS FOR THE ALKYLATION F ISQPARAFFIN Sarrand Parker, Los Angeles, Calif., assigner to Union Oil Company ofCalifornia, Los Angeles, Calif., a corporation of California ApplicationJanuary 30, 1939, Serial No. 253,502

6 Claims. (Cl. 196-10) This invention relates to the treatment ofhydrocarbon oils, and refers more particularly to the production ofvaluable gasolines by synthetically reacting the lighter and vlessvaluable portions of crude petroleum products and similar hydrocarbonmixtures.- In a more specic sensa' the invention has reference to aprocess which may be employed to supplement known crude oil treatingprocesses to increase the obtainable yield of high anti-knock fractionssuitable for use as fuel in internal combustion engines, or as con- Thecomparatively recent adoption of high compression ratios in automobileand aviation er1- gines to increase their thermodynamic efficiencyplaced ademand on .the 'petroleum refining and similar industries tofurnish hydrocarbon motor fuels of high anti-knock or slow burningcharac' teristics. As a partial attempt to satisfy this requirement thepetroleum industry has resorted to the use of cracking operations inwhich the relatively higher boiling hydrocarbon fractions are fraction,it also contains other petroleum hydrocarbons, including appreciablequantities of olens ranging from ethylene into the normally liquidoleiinic hydrocarbons which have been carried out of the cracking zoneby the released gases. `frenerally, in modern renery operations, thesehydrocarbon fractions are subjected to a 'treatment With an absorbingmedium to recover most if .not all of the entrained normally liquidhydrocarbons. The remaining gaseous fraction contains varyingproportions of oleflns of the type of propylene and butylenes, as wellas some'saturated hydrocarbons such as methane,

subjected to elevated temperatures and frequently super-atmosphericpressures to cause the decomposition of these hydrocarbons and toproduce fractions within the motor fuel boiling range.

However, these cracking operations are not entirely satisfactory bothfrom the'standpoint of yields and the quality of the produced motorfuels. Thus, among other objections, the motor fuels derived from suchcracking of petroleum oils or their fractions do not possess the desiredhigh anti-knock characteristics. Nor are these fuels sufficientlysusceptibleto the action of substances of the type of tetraethyl lead.-In other words, such lead compounds, when added in quantities withinthe permissible range, are incapable of raising sufficiently theknock-rating characteristics of the motor fuel fraction thus treated.Furthermore, all cracking processes produce more or less appreciablequantities of normally gaseous hydrocarbons of varying compositionswhich, if

not utilized, represent Wastednatural resources.

These normallyv gaseous fractions, resulting as a by-prcduct from thecracking of petroleum o ils, contain considerable proportions ofoleflns, particularly of the type of propylene and butylenes. Inconnection with the operations of most modern petroleum refineries,there are several sources of such olefin-containing normally gaseousfractions. One of these is the gaseous fraction produced as the resultof releasing the pressure on the petroleum oils which arebeingjsubjected to a cracking treatment. Although relatively largepercentages of methane are usually present in this ethane, propane andbutanes. Another source of -therenery gases is the overhead or refluxfraction obtained from the stabilization of pressure distillateresulting from cracking petroleum oils under pressure. These fractionsgenerally predominate in oleiines of the type of propylene andbutylenes, usually containing only very small percentages of methane.'Obviously, the composition of the different. gases will varyconsiderably depending on the stock subjected to cracking, as well as onthe specific cracking and recovery processes employed.

Recently, it has been proposed to produce synthetic motor fuel fractionsby contacting isoparaflinic or aromatic hydrocarbons with olens in thepresence of a suitable catalyst adapted to produce a chemical combiningof these hydrocarbons. The resulting product may be termed a product ofalkylation, and may be generally described as consisting of saturated orcyclic hydrocarbon'molecules with hydrocarbon chains or branchesattached thereto. The above nomenclature was employed to distinguishthis branched chain molecule from a polymer which is a product resultingfrom the interaction of two or more oleiinic molecules to produce anunsatup rated hydrocarbon molecule having a correspondingly highermolecular weight. i As an exn ample of an alkylation reaction and of theresulting product, reference may be made to the chemical combining ofpropylene or butylene with isobutane to produce seven or eight carbonatom.

branched chain saturated molecules, respectively.

It has been recently discovered that optimum treatment of isopentanewith butylene or propylene may cause the production of excessivequantities of polymers. For this reason it has been generally consideredadvisable to produce relatively narrow cuts or fractions predominatingin a given isoparaffln, and to catalytically alkylate these individualisoparafiinic fractions with the olens to produce optimum yields ofproducts of alkylation. Furthermore, since normal paramns do not reactwith oleiins unless subjected to decomposing temperatures and pressures,it is adof the isoparaiiin-containing drocarbon fractions.

visable to fractionate the paraiiinic hydrocarbons so as to isolate theparticular isoparailin even from its corresponding normal parafiinichydrocarbon before the isoparainic hydrocarbon fraction is employed inthe alkylation reaction. Obviously such procedure necessitates the useof specialequipment for the narrow fractionation of the saturatedhydrocarbons, thus greatly increasing the initial and operating costs ofan alkylation plant.

As previously stated, products of alkylation are formed by the catalyticinteraction of isoparaiiins and olens. Generally, this alkylation isconducted -in a liquid phase, the liquefied isoparailns such asisobutane or isopentane being iirst intimately commingled with theliquefled olefin-containing fraction before the mixture is brought intocontact with the alkylating catalyst such as sulfuric acid, a mixture ofsulfuric and phosphoric acids or a metal halide catalyst such asaluminum chloride. Since the oleiins are re1- atively highly reactiveand tend to form polymers or isoparafnic hy- A further object of theinvention is4 to provide an alkylation process for the production ofhigh anti-knock motor vfuel fractions in which process the separatefractionation of the isoparaiiinic hydrocarbon is eliminated.

, A still further object of the'present invention is to conduct thealkylation of isoparailinic hydrocarbons, and preferably the isobutane,isopentane and/or isohexane fractions with normally gaseous oleiins andolefin-containing gases, in a liquid state and in the presence of acatalyst of the type described above, without the necessity of providingmeans for the expensive compression and liquefaction of theolefin-containing by contacting this liquid medium, and the olens inpreference toA their alkylation of the isoparaffins, it is desirable, ifnot essential,` to maintain an excess of the isoparalnic hydrocarbonfraction, or of the products of alkylation. Although y the isoparaflinichydrocarbon employed for the production of high anti-knock motor fuelsmay be obtained from other sources, these isoparaffins, and,particularly isobutane, isopentane and isohexane, are mainly derivedfrom the stabilization of gasolines extracted from natural gases. Thus,although the fractions employed as reflux for such natural gasolinestabilization are in a liqueed state and predominate. in propane, thesefractions may in turn be fractionated to produce an isobutanepredominating cut. A comparable material may be produced as a side-cutduring stabilization of the natural gasoline. The isopentane andisohexane fractions may be recovered from the fractionation ofstabilized natural gasoline. On the other hand, the oleiinic fractionsobtained as a by-product from cracking operations are often in a gaseousstate so that if the alkylation reaction is to be realized in a liquidstate, these olefin-containing gases must be liqueed, thus furtheradding to the cost of the operations.

It is, therefore, the main object of the present invention to avoid theabove diiiiculties and to provide la novel process forobtainingfincrea'sed yields of high anti-knock motor fuel fractions bymeans of new and, novel cooperation of certain steps to be describedmore fully hereinbelow. A

l further object of the present invention is to obtain a motor fuelfraction having a high antiknock value and substantially free fromproducts of polymerization by processing a mixture of normally gaseousolefin-containing hydrocarbons derived from petroleum oil conversmn orcracking thus liquefied, with the liquid isoparaiiinic hydrocarbons, atoptimum temperatures and in the presence of an alkylating catalyst, suchas strong sulfuric acid. The resulting product of alkylation, or someportion or fraction thereof may be used as the absorbing medium. By suchoperation, the liquid product of alkylation is thus emprocesses, andliquefied saturated normally gase-` ons hydrocarbonstcontainingisoparaiiinic fractions without the necessity of providing special or,girate equipment for the narrow fractionation -ployed both forthepurpose of absorbing (and thus liquefying) the oleiins, and todilute, and thus lower the concentration of oleflns in the reactionzone, thereby promoting the alkylation of the introduced isoparamns,with the concurrent inhibition of polymer formation.

It has also been discovered that a considerable saving in initial andoperating expenses may be realized by eliminating any specialfractionating structures for the recovery of the substantially pureisoparainic fraction, such as isobutane, iso'- pentane or isohexane,vfrom the hydrocarbons containing the same, and by fractionally treatingthese isoparafiin-containing hydrocarbons `together with the crudeproducts of alkylation revcovered from the catalytic treatment ofisoparaflins with oleflns.

It is to be noted that the crude liquid fraction produced as a result ofthe interaction of an isoparafllnic fraction (such as a hydrocarbonfraction predominating in isobutane) with an olefin-containinghydrocarbon4 fraction, comprises a heterogeneous liq'uid mixture whichcontains true products of alkylation, relatively large percentages ofthe isopara'iilnic hydrocarbon being alkylated, and relatively j smallerquantities of other gaseous hydrocarbons which havebeen dissolved intheliquid product. Furthermore, even the true products of alkylationthemselvesrcomprise ar mixture 4of hydrocarbons having different boiling-points resulting from the chemical combining of the isoparailins withthe different oleiins entering thereaction zone. In view of thisheterogeneous character of the crude product, the separation andrecoveryof the desired hydrocarbon fraction boiling within the gasolinerange, necessitates a fractionation of the crude reaction product.According to petroleum cracking operations.

' from the specific isoparaiiin, such as isobutane,

in a substantially pure state, this isoparaftinic fraction beingrecovered as a liquid and utilized asthe feed or starting material forthe formation of additional quantities of products of alkylation.

The invention further includes processes in which the above outlinedstepsrare 'employed' in combination withother steps such as: therecycling of a portion of the crude products of alkylation to maintainsuitable ratios of products of alkylation, isoparalns and oleflns in thereaction zone; recycling of the acid and/or hydrocarbon acid mixture oremulsion to alkylate new quantities of isoparafllns and olens;dehydration of the hydrocarbons prior to their introduction into thereaction zone and into contact with the catalyst such as strong sulfuricacid; and the desulfurization of the olefinic hydrocarbons. Theinvention further includes an alkylation process of the classdescribedin which a portion of the products of alkylation, andparticularly the heavy fraction boiling above the gasoline boilingrange.' may be efliciently em# ployed as the medium for the heating ofthe various fractionating towers, thus furnishing the heat necessary forthe fractionation of the'crude alkylation reaction product and of theisoparanim-containing hydrocarbons.

The invention will be further understood from the following descriptionof an -embodiment of the invention, this description being made withreference to the accompanying drawing which forms a part of thespecification and which represents a diagrammatic elevational view of anapparatus suitable for carrying out the ,pres-l ent process.

Referring to the drawing, the olefin-containing normal1y` gaseoushydrocarbon fraction is Since in thefpresent process the alkylationreaction described more fully hereinbelow is conducted in a liquidphase, the oleflnic fraction introduced through line I may be a portionof the condensed reflux fraction obtained during the stabilization ofpressure distillate resulting from `In the alternative, the overheadgaseous 'fraction derived during such stabilization of cracked pressuredistillate may also be used as the' charging stock. Obviously, suchgaseous fractions should bepreliminarily condensed by any suitable andknown methods and means. Both the overhead gaseous fraction and thereflux portion thereof contain relatively large quantities of oleiins,the propylene-butylene content of such fractions 'usually exceeding 20%,and in most cases being above 30% or even 35%.

The so-called lean gases resulting from the ordinary absorptiontreatment of gaseous fractions produced during the release of pressureon the crackedpetroleum product, are also a suitable source for theobtaining of olens which may be employed in the alkylation process. ousfraction, although containing relatively large quantities of methane andethane, also contains appreciable proportions of olefins of the type ofpropylene and butylenes which are suitable for use in the process to bedescribed. Thus, these lean gases contain -as much as to 15% ofpropylene and butylenes. These lean gases may be introduced into thesystem through line I2,

This gase-,

. charged into the system through conduit I0.-

wherein they are rst cooled as by passage through a chiller I3. Thischiller may be eliminated if the gases are available at a suitably lowtemperature. In order to obtain a liquid olefin-containing fraction, aswell as for the purpose of selective extraction of the desirableolefins, these cooled lean gases are then passed into an absorber I4 inwhich they are brought into contact with a fraction of the products ofalkylation. As will be described more fully hereinbelow, the lean oilused vin the present process as the absorbing medium in absorber I4 isthe heaviest fraction resulting from the fractiona tionof the productsof alkylation.` It is to be understood, however, that other fractions ofthe products of alkylation, as well as other absorbing media, may beused to extract the desired olefins from the lean gases.

The lean oil to be used in the above described absorption is firstcooled in a heat exchanger I6 and-is then'continuously fed through lineI1 into absorber I4. The rich oil thus formed (comprising the productsof alkylation and the olefincontaining gases absorbed thereby) isWithdrawn through line I8, and, after further cooling in heat exchangerI9, is conveyed through line 20 and into line I0 to be commingled withthe first mentioned liquefied olefin-containing gaseous fraction. 'Thegases which are not absorbed by the lean oil are removed from the systemthrough line 22 leading from the upper part of absorber I4.

The liquid fraction thus entering the system through line I0 is rstsubjected to a desulfurization operation for the removal of the hydrogensulfide usuallypresent in the olefin-containing normally gaseoushydrocarbons. Although the hydrogen sulde content of such hydrocarbonsis relatively small, being in the neighborhood of 0.25%, it has beenfound that the removal of this sulfide is beneficial and results inbetter yields of products of alkylation, as well as in greater economy.To effect the removal of the hydrogen sulfide the olefin-containingliquid fraction is conveyed into a vessel 25 wherein it is vbroughtlinto contact with an aqueous solution of an alkaline compound having an`ainity for hydrogen sulfide. As an example, vessel 25 may be filled withan aqueous solution of sodium carbonate. The desulfurized hydrocarbonsthen leave the vessel 25 through line 26, while the sodium carbonatesolution containing the absorbed sulfur compound is withdrawn throughline 21 and conveyed into the top of a regenerating vessel 28 in'whichthe foul sodium carbonate is brought in contact with an upward draft ofaair introduced through line 3|. The rejuvenated sodium carbonatesolution is then withdrawn from the bottom of tank 28 and is returnedthrough line 29, either continuously or intermittently, back into vessel25 for further desulfurization of the olen-4 containing hydrocarbonfractions. The air contact with such strong sulfuric acid catalyst. A

paraiiins of the 4type of isobutane, isopentane and` isohexane is bestrealized in the presence of a relatively strong sulfuric acid, forexample'sulfuric acid having approximately a 98% H2804 content.- Sinceany water present will naturally dilute the sulfuric acid catalyst, itis desirable to dehydrate the hydrocarbons prior to their con-Therefore, for the purpose of removing any Water which may be present inthe olefin-containing liquid hydrocarbon fraction, the desulfurizedfraction leaving vessel through line 26 is conveyed through a drier 34which may contain any known drying material such as sodium sulfate.Although only one such drying tank is shown in the drawing, it isobvious that a plurality of such tanks may be placed parallel so thatany one of the tanks may be isolated for the purpose of regenerating thesodium sulfate or for the purpose through line 55. Obviously, whennecessary the neutralized alkali may be withdrawn from the systemthrough line 53, whilev fresh alkali may be introduced into the systemthrough the same or another pipe.

The neutralized hydrocarbon mixture, comprising products of reaction andunreacted isotroduced through line 4I and with used catalyst between theisoparafiins and the oleiins, it isv desirable, if not essential, tomaintain an excess of the isoparaftns and of the crude products ofalkyation. Obviously, the presence of excess isoparains (such asisobutane) in the hydrocarbon mixture passing through mixer 44 resultsin the presence of unreacted isoparailins` in the stream being conveyedtherefrom through line 46. After passage through cooler 45, thishydrocarbon stream (while in ya state of emulsication or commingled withthe sulfuric acid or other catalyst) is divided into two p ortions. Oneof these is conveyed through lines- 48 and 36 for purposes of recyclingwhile the other is conveyed through line 49 into settler 50. Thesulfuric acid settlesl to the bottom of this Vsettler 50 and iswithdrawn through line 52. As stated, this acid may be recycled byconveying it through line 42 which leads this acid catalyst to line 4I)wherein it is continuously commingled with fresh'quantities ofhydrocarbons to be alkylated. The acid when incapable or uneconomicalfor alkylation of further quantities of isoparaflins and olens, may bewithdrawn through line 53, while, as stated, fresh acid or the like maybe introduced into the system throughline 4I.

The supernatant layer, comprising the prodtator 51, and is then passedthrough line 58 into` another settler 59. Here', the sodium hydroxidedeposits itself to -the bottom and may be withdrawn from the bottomthrough line 60. This vneutralizing agent may then be recycled throughlines 62 and 56 for the washing of further quantities of thehydrocarbons being conveyed parains, is continuously withdrawn as thesupernatant layer, 'from settler 59, and is conveyed through line 66 toa fractionating system to be described more fully hereinbelow.

' In view of the fact that the alkymtion re- 66 are .first conveyedthrough heat exchanger 68 in which they are brought into indirectcontact with the isoparailinic fraction (such as isobutane) passingthrough line 84 to dehydrating tank 31 from which the liqueiied coldisoparailins are then conveyed to the alkylating zone` described above.

After passing through heat exchanger 68, the

slightly warmed hydrocarbon mixture is then conveyed through line 69 toa surge tank 10, from which the mixture is conveyed through line 1I,heat exchanger I9, line 12, and heat 'exchanger I6. In the rst ofthese,- heat exchangers, the hydrocarbon mixture precools theolefin-containing labsorbing medium passing through lines I8 and 20,while in lheat exchanger I6, the products of reaction are heated by thelean absorbing medium fed into absorber I4 through line I1. 'The mixtureof preheated reaction products leaving preheater or heat exchanger I6 isconveyed through line 14 into the rst of a series offractionatingcolumns. However, prior to such introduction into thefractionating system, the crude products of alkalation are rstcommingled with an isoparaiiin-containing fraction introduced into thesystem through line 15. As previously stated, this isoparafn-containingfraction may be a hydrocarbon mixture containing both normal andisomericparailins (such as normal butane, isobutane, etc.), thishydrocarbon mixture being derived either as a side-cut or fraction, oras a reux fraction in the stabilization of natural. or straight rungasolines.

The fractionation of the lsoparafn-containing hydrocarbons and of theproducts resulting from the alkylation reaction is realized according tothe present invention in a plurality of fractionating columns. As shownin the drawing,.the mixture passing through line 14 iirstV entersfractionator 11 which maintained at optimum temperatures and pressuresto cause the vaporization of thelightest hydrocarbons of the type ofmethane, ethane, and propane. The heating of fractionator 11, as well asof the succeeding fractionator, is realized by method and means to bedescribed more fully hereinbelow. The hydrocarbon vapors in fractionator11 are withdrawn therefrom through line 18. A portion of this overheadfraction is cooled at 19 and the condensate thus formed is returned asreiiux through line 83 back into the upper portion of fractionator 11.The remaining portion of the gaseous overhead fraction may be withdrawnfrom the system through line 82, while any noncondensed gasesy fromcooler 19 may be withdrawn through line 83. The hydrocarbons remainingin the liquid. state in fraction- 'ator 11 are withdrawn from the bottomthereof through line 85 and are conveyed therethrough, to the secondfractionator 86. A portion of the bottom fraction thus withdrawn throughline 85 is by-passed through 81 and is conveyed through these productsof alkylation, the hydrocarbons in fractionator -tionation so as toobtain three cuts. By mainwhich may comprise a hydrocarbon fractionsuita heater or reboiler 88 and then returned through line 89 back intofractionator 11 -to provide the above described heat necessary for thevaporiza-l tion of the propane or the lighter gaseous hydrocarbons. Theheat for the reboiler 88, as stated nating in or substantiallyconsisting of isobutane.v

For this purpose fractionator 86 is maintained at a desired or optimumtemperature or pressure.`

The overhead fraction formed is withdrawn from the top of thisfractionator through line 9|, condensed in cooler 92, and a portionreturned through line 93 back` into fractionator 86, this liquefiedhydrocarbon fraction acting as a refluxing medium. The remainingisobutane fraction condensed at 92 is conveyed through line 94 for useas the isoparaiiinic hydrocarbon fraction to be alkylated. For thispurpose, this isobutane fraction is first partially precooled bypassingit through the heat exchanger 68 and through tank or drier .31 inwhich the hydrocarbon fraction is dehydrated as by means ofsodiumsulfate or a similar desiccating medium. The dried isobutane, asdescribed above, thus passes through line 39 to lines 36 and 40 whereinit is commingled with crude products of alkylationfolens and the acidcatalyst.

The hydrocarbon mixture remaining as a liquid in fractionator 86 iswithdrawn from the' bottaining fractionator 98. at optimum temperaturesand pressures an overhead fraction is' produced,

able as a fuel for aviationengines. Thus by suitable operation of thefractionator 98 it is possible to obtain an overhead fraction having anend point of about 325 F. which is the end boiling point of aviationgasoline. This overhead fraction is removed from the top of fractomthereof through line 91 and is conveyed to.

the last fractionator 98.. As` in the case of the first fractionator 11,a portion of the bottom fraction withdrawn by 91 from fractionator 86 isby-passed through line 99 and is conveyed ator through line |0I. Insteadof by-passing only aportion of the bottom fractions withdrawn fromfractionators 11 and 86 through lines 81 and 99 respectively, it isalso. possible to convey the whole bottom fractions through theirrespective reboilers or heaters 88 and |00. In such a case the vaporizedportions therefrom in these reboilers may be returned through lines 89 Yand |0I to their respective fractionators for the purpose of providingthe necessary heat for fractionation therein. Unvaporized hydrocarbonfractions may then be withdrawn from the reboilers and conveyed -to thesucceeding frac-v rtionator 98 through line |05 and ls condensed v Aportion of liquefied gasoline. fractions is returned through line |01back into in cooler |06.

the fractionator and is used therein as a `reflux medium, 'while theremaining aviation gasoline fraction is withdrawn from the systemthrough v line |08. The heavier synthetic gasoline fraction is withdrawnas a middle or side-cut through line |09 and may be condensed in I0.This synthetic productv of alkylation, although having a higher endpoint than the overhead fraction withdrawn through line |08, alsopossesses-good anti-knock characteristics and is particularly suitableas a motor fuel for automobiles or as a 'constituent thereof.A 'Iheresidual fraction remaining unvaporized is withdrawn from the bottom ofthe fractionator 98 through line i2. A portion of this fraction isby-passed through line ||3, precooled in heat exchanger |6 and is usedas the'absorbing medium in absorber I4. Of the remaining residualfraction withdrawn from fractionator 98, a portionis by-passed throughline H4 for use as the heating medium for the fractionating system. Forthis purpose it is conveyed through said line III to a heater ||5wherein it is raised to anoptimum or desired temperature. This heatedhydrocarbon fraction is then conveyed through line ||6 and is employedfor heating reboilers 88 and |00 and to provide heat in fractionator 98.For this purpose line ||6 communicates with branch lines spectively, thebalancevof the heated hydrocarthrough heater |00 and back into thefractioninto the bottom portion of fractionator 98. After passingthroughreboilers 98 and |00 the heating medium is returned through lines |22and |23 respectively back into line H4 leading to heater H5.' The netexcess heavy products of alkylation withdrawn through line ||2 areremoved from .the system through line |24, provided with a valve |25. X

As indicated above. the description of the lprocess is simplyillustrative o1' the invention and is subject to many modifications bythose skilled in the art. Thus, although the use oi lysts.

tem to be used for various purposessuch as i stabilization of pressureAdistillate or natural gasoline, or it may be subjected to isomerizationto form additional quantities of isobutane, thus .in-

creasing the potential yield of products of alkylation. The liquidhydrocarbon fraction introduced through line 91 into the lastfractionator 98 predominates in products of alkylation. However, inviewy of the relatively wide boiling range oi 98% and strong sulfuricacid is above indicated it is obvious that the process may be realizedwhile employing other'alkylating catatween about 94% and 100% H2804content may be employed. Also the catalyst vmayconsist of a mixture ofsulfuric and phosphoric acids or may compriseor. include chlorosulfonicacid or certain metallic halide-complexes such as aluminum chloride orboron triuoride or catalysts consisting of the above acids incombination with certain metallic salts such as phosphates, -sulfates,chlorides, nitrates and acetates ofthe type of cadmium, zinc, silver,mercury, copper and barium may be used. Thesesalts act as vactivators topromote the alkylation reaction in preference tol the polymerization ofthe oleflns.

98 may be subjected to a frac- Generally speaking,'sulfuric acid of be-yploying 'said alkylation products tion with the recycling ofaportionofthe hydro-f carbon acid mixture through lines and 48, it is possibleto recycle a portion of the crude prod-y uctsof alkylation fromline-ilback intoline Il,"

' lutejthe'olefins and maintain alproper ratio between the products lofalkylation,"isoparailins and liquid mixture containing the absorbedloleilns,

oleilns. Such a `procedure would eliminate any extensive contact betweenthe crude products o! alkylation andthe acid. Furthermore, instead oi'employing both the oleiln-containing fractionv lyst, thereby formingreaction products compris-A ing said 'branched chain saturatedhydrocarbons, l

derived from the stabilization of pressure distillate and' that obtainedfrom the reduction ofi pressure inthe cracking stills, it is possible touse either of these fractions or any other olencontaining fraction,vespeciallyuif it is lrichin the desirable propylene and butylenes.Furthermore,

accesos. Although the process isdescribed' in connecgasoline rangewherein" 'isoparamnic hydrocarbons arek reacted with normally gaseousoleiinic hydrocarbons inlfthe presence oan alkyiating catalyst,theysteps o! v contacting the gaseous oleiins "with a 'hydrocarbonliquid absorbing medium oriorto ooniaot with said isoparamnf andalkylating catalyst, thereby -producing a 'commingling said mixturewithliqueiied iso' oaramnsio be alkyiotedfand the aikylaungoatsseparating the alkylation'products from the alkylating catalyst,fractionally distilling the -said tion anda fraction containinghydrocarbons boil-'f v ing above the gasoline boiling range and,1employ-l 1 ing said fraction'containing. hydrocarbons boilthe absorptionoi' the olens li'rom the 'gases en- "1 tering through I2 'may berealized by any other absorbing medium or by a portion of the products iof alkylation as formed according to of the present invention.'

The. heating of the reboilers may be realized the process byv employinghydrocarbon fractions other 'than the heavy reaction products removedfrom the parafllns are caused to react in the presence oi bottoni of,fractionatorv ll. Furthermore, other'v heating media such as steamV may4be employed for this-purpose. Still further incarryingvout theinvention the conditions oi! operation chosen with respect totemperature, proportion of reacting-l constituents, choiceso'i'catalysts, and temperatures andv pressuresl inthe fractionating systemVmay be varied within a relatively large Vrange to suit the individualcase. Therefore, the above disclosure is merely illustrative and 'is notto be taken as limiting since many variations may be possible withinthe'scope oi the pending claims.- q a i I claim:

l. In a process for the production' 'of branched" chain saturatedhydrocarbons'boiling within :thel

gasoline range wherein isoparamnic hydrocarbons are reactedwith'normally gaseous oleflnic hydrocarbons in the presence of analkylatirxg u catalyst, the steps o! contacting the gaseous oletlnswitha hydrocarbon liquid absorbing medium i' prior to contact with saidisoparaillnand 'alkyling above the gasoline boiling range as saidhydrocarbon liquid absorbing medium.

v4. In a process for the production of branched chain hydrocarbonswherein oleilns and isoa sulphuric acid catalyst, the steps ofcontinuously recycling a mixture oi isoparailins, products oi' reactionand the acid in a closed system, con- -V tinuously contacting gaseousoleilns with a liquid absorbing medium, continuously introducing intosaid system gaseous oleilns dissolved in said liquid absorbing mediumand isoparaiilns to be reacted,

i. continuously withdrawing from said system Ia ating catalyst therebyproducing a liquid mixture said mixture with liquefied. iscp'arailns to'be al, kylated and withthe alkylating catalyst thereby formingalkylation products, comprising said branched chain saturatedhydrocarbons and emabsorbing medium.- l 2. In a process for theproduction of'branched chain saturated hydrocarbons boiling within thegasoline range wherein isoparailinic hydrocarbons are reacted withnormally gaseousjolenic w' hydrocarbons in the presence o! an alkylatingcatalyst, the steps' oi' contacting the gaseousl `oleilns with ahydrocarbon` liquid absorbing ing said branched chain saturatedhydrocarbons, 70

separating said reaction products into fractions and employing one ofsaid` fractions as the said absorbing medium.y f

. 3. In a process for the production of branchedv chain saturatedhydrocarbons boiling within the l oontainmg. the absorbed olenos.oommmgung .o

as said liquid 55 portion of Ithe hydrocarbon-acid mixture,vcontinuously settling,l said .withdrawn mixture thereby obtaining alhydrocarbon phase containing the products of alkylaaomreeotioo and anacid phase, 7 separatingy said phases, returning the acid phase Aintorthe closed reaction system for the alkylation oi lfresh quantitiesof isoparaillns and oleilns introduced .thereinand employing a portionoi the products o! alkylation as, said liquid absorb# ing medium. 5. Acontinuous process for the alkylation of isoparailinic hydrocarbonshaving less than seven carbon atomspermolecule with normally gaseousoleilns to producebranched chain saturated hy-v dro'carbons boilingwithin the gasoline range,

v having highanti-detonating characteristics and substantially free fromproducts of polymerization, which'comprises'continuously contacting thenormally gaseous oleilns with a liquid hydrocarbon absorbing medium toproduce a liquid mixture containing the absorbed oleflns, continuouslyintroducing said liquid mixture and a substantially pure isoparaillnichydrocarbon fraction boiling within a relatively narrow boiling rangeand maintained in a liquid state into a reaction zone, continuouslyintroducing strong sulphuric acidinto said zone to cause the interactionbetween th'e isoparaiilns and the oleilns to form products ofalkylation, .continuously recyclinglsaid hydrocarbon-acid mixturethrough said re,-

action zone, continuously withdrawing a portion oi' said mixture fromthe reaction zone, continu'- ously separating said withdrawn mixtureinto an acid phase and a hydrocarbon phase containing the products oi'reaction and the unreacted isoparaillns, separately withdrawing saidphases; commingling the hydrocarbon phase with aniso#paraiiin-containinghydrocarbon fraction, continuously conveying saidmixture through av fractionating zone to recover therefrom the desiredbranched chain hydrocarbon fraction and a liqueed, substantially pureisoparainnic hydrocarbon fraction having a relatively narrow boilingrange, returning said last mentioned hydrocara1ky1ation productsmtoasynthouo gasoline fraoo bon fraction as the feed stock for theproduction of new quantities .of branched chain hydrocarbons, wherein afraction of the products of reaction comprises the absorbing medium forthe gaseous oleflns.

6. A continuous process for the alkylation of isoparaflinic hydrocarbonshaving less than seven carbon atoms per molecule lwith normally gaseousolens to produce branched chain saturated hydrocarbons boiling withinthe gasoline range, having high anti-detonating characteristics andsubstantially free from products of polymerization, which comprisescontinuously contacting the normally gaseous'olens with'aliquidhydrocarbon absorbing medium to produce a liquid mixture containing theabsorbed oleflns, continuously introducing said liquid mixture. and asubstantially pure isoparaiilnic hydrocarbon fracvv tion boiling Withina relatively narrow boiling range and maintained in a liquid state intoa reaction zone, continuously introducing strong :r-ulphuric acid intosaid zone to cause the interaction between theisoparallins and the olensA:o form products of alkylation, continuously recycling saidhydrocarbon-acid mixture through said reaction zone, continuouslywithdrawing a portion of said mixture fromthe reaction zone,

continuously separating saidv withdrawn mixture intoan acid phase and ahydrocarbon phase tion boiling above the gasoline boiling point range land a substantially pure isoparailinic hydrocarbon fraction having arelatively narrow vboiling range, returning the said isoparailinicfraction having the relatively narrow boiling point range as the feedstock for the production` of newquantitiesV of branched chainhydrocarbons and employing said heavy -alkylated 'hydrocarbon fractionas the said liquid absorbing medium.

FARRAND D. PARKER-

